Aeroplane-propeller



E. W. SUMMERS.

AEROPLANE PROPELLER.

APPLICATION FILED our. 23, 1917.

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A TTORNE Y E. w. SUMMERS.

AEROPLANE PROPELLER.

APPLICATION FILED OCT- 23, I917.

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A TTORNEY EDGAR W. SUMMERS, 0F PITTSBURGH, PENNSYLVANIA.

AEROPLANE-PROPELLER.

Specification of Letters Patent. P t t d D 28 1920.

Application filed October 23, 1917. Serial No. 198,029.

To all whom it may concern:

Be it known that I, EDGAR W. SUMMERS, a resident of Pittsburgh, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in Aeroplane-Propellers, of which the following is aspecification.

This invention relates to air screws or propellers, and moreparticularly to screws or propellers for use in aeroplanes, dirigibles,balloons, etc.

W'hile it has been proposed to form aeroplane screws or propellers fromsheet metal, such propellers are today largely made of wood, generallylaminated. They are roughly shaped by machinery but the final shapingmust be done by hand, and since the contour must be very exact,specially skilled men are required for finishing them. It has been foundthat few men can be trained for this work, but that it requires men whohave a knack or special aptitude for the work. The result is that themanufacture of such propellers is not only slow and expensive, butbecause of the inability to train men for finishing them, the output is,and must necessarily be, rather limited.

Furthermore, these propellers usually comprise two blades in a singlepiece, and it is the practice to hand finish the complete propeller soas to have the same accurately balanced, and in the event that any oneof the blades is injured, it is necessary ture to take off a blade atone end and reto discard the entire propeller as it is not possible inthe present methods of manufacplace it with another.

Furthermore, there is always danger of the wood warping after the bladeis finished, and the laminated wood is also affected by climaticconditions, such as heat and moisture. Also, in making these woodenblades, due to the twist which must be in the blades, the wood isnecessarily cut insome part of the blade across the grain and frequentlythe blades break at these cross-grain portions.

The object of my invention is to provide a propeller blade which is freefrom-the difficulties above mentioned; one which can be expeditiouslymade in large quantities and without requiring men having such a highdegree of skill or special adaptability as above mentioned; which ismade in such way that each and every blade of a given size and designwill be an exact duplicate of every other one, so that in case a bladeis injured it will be possible to substitute a new blade from stock; onewhich is stronge" than a wooden blade and in which the stresses can becalculated and the blade reinforced with material of a known strength toresist the stresses; and one which is not affected by climaticconditions.

For the attainment of the foregoing objects the propeller blade isformed by die shaping sheet metal, preferably in parts, and unitingthese parts to form a hollow body whose external contour conforms to thebest propeller shape or design, said body being internally bracedagainst collapse and internally reinforced wherever required to providethe necessary strength.

The accompanying drawings illustrate one form of the improved propeller.In these drawings, Figure 1 is a face or plan View of one of the blades;Fig. 2 is a transverse section thereof on an enlarged scale, on the line2-2, Fig. 1; Fig. 3 is a face view of the hub portion of the propellerillustrating one manner of connecting the blades to the hub; Fig. 4 is asectional View on the line 44 of Fig. 3; and Figs. 5 and 6 are viewscorrespondlng to Figs. 3 and 4 (Fig. 6 being a section on the line 6-6,Fig. 5) and showing a modified form of construction.

The drawings show the external shape of the propeller blade only in ageneral way, it being understood that the exact external contour will bevaried to meet different conditions, and can be made anything that thebest engineering practice may dictate. Such blades, as is well known,have a twist from the hub or boss end to the tip end, and this isindicated in a general way 1 n Fig. 1, but has not been illustrated indetail because the invention merely has to do with the construction ofthe blades, which construction' can be adapted to various con.

forming what may be termed the flatter'or the working face of the bladeand a sheet 3 forming the more rounded or curved face of the blade. InFig. 1, the face 2 of the propeller is shown, and in Figs. 1 and 2, theedge portion marked 4 is the forward or air clevage edge of the bladeand the edge marked 5 is the rear edge thereof. The arrows on thedrawings indicate the direction of rotation. The two plates 2 and 3 havetheir edges secured together all around the blade in any suitable way,such, for instance, as by soldering or brazing, but preferably bywelding, which can be expeditiously done by the electrical process.These sheets will be formed to the desired contour by pressing in dies,and obviously after a set of dies have been accurately made, thencomparatively unskilled labor can produce the sheets in almost unlimitedquantities, and with the assurance that all sheets will be exactlyallke, thus insuring propeller blades which are exact duplicates of eachother.

These blades can be made of very thin sheet metal, thus rendering themvery light, and in order to strengthen them against collapse, they canbe, and preferably are, internally braced and reinforced in any suitableway. Figs. 1 and 2 show one form of bracing, the same comprising a metalsheet 6 extending lengthwise of the blade for the major portion of itslength and formed into a zig zag or corrugated shape and united to thetwo face plates alternately, as at the polnts 7 and 8 respectively. Thisunion can also be formed in any suitable manner, but preferably byelectric welding as above described.

In constructing the blade, the sheets are first die pressed to theproper shape, after which the brace member 6 is united to one of thesheets, such as by welding it to the sheet 3 at the points 7. The othersheet, such as sheet 2 is then welded to the brace member at the points8, the inner terminal of the electric welder being inserted through theopen hub or. boss endof the blade. Lastly, the edges of the two sheetsare welded together as above described.

While assembling and welding these parts, they are held in suitable jigsto hold them in proper shape and in pro-per position relative to eachother.

The blade is reinforced to give the necessary strength at any point, andespecially at the boss or hub end where the stress is greatest. Suchreinforcement is preferably applied internally so as not to interferewith the external contour of the blade. The'brace sheet 6 reinforces thebody of the blade, and

such as by electric welding. These reinforcing members at their hub endsare widened out to conform to the shape of the blades 2 and 3, and theyextend toward the tip for the desired distance and gradually taper offor become narrower as they extend outwardly. If great strength isrequired, several such reinforcing plates of progressively cylindricalform externally and the blades at their hub ends are widened out to formsegmental portions 13, each extending for approximately 120 degrees andfitting against the exterior of the hub 12. Inside of the portions 13 ofthe blade is a rmg shaped brace member 14, preferably having its edgesflanged, as at 15, to extend toward the boss or hub, and secured to theblades, such as by welding the flanges 15 to the inner faces of theblades. The abutting edges of adjacent blades are also welded together,such as on the lines 16. On each face of-the propeller is provided asheet metal ring or face plate 17 which is welded along its edge to theblade, on the line 18, or at any other desired places, and which has itsinner edge flanged outwardly, as at 19 and welded to the boss or hub 12.

In assembling the propeller with this construction, the blades with thereinforcing plates 9 and 10 secured therein are assembled in a suitablejig with the interior bracing ring 14, the abutting edges of thesegmental portions of the rings are welded together on the lines 16,after which the face plates 17 are put in place and welded at theiredges 18 to the outer faces of the blades at one an the same time thatthe ring 14: is welded to the inner faces of the blades at 15. Betweenthe blades on the periphery of the hub where there would otherwise beopen joints, small pieces of plate 20 are welded to the outer face ofthe segmental portions 13 of the blades. All of this welding must bedone before the boss hub is put in place in order that one of thewelding terminals can be gotten to the interior of thewheel. Finally,the hub is put in place and welded to the flanges 19 of the plates 17Figs. 5 and 6 illustrate a construction in which the blades are fastenedto the hub in a manner to permit any one of the blades to be readilyremoved and replaced by an,- other. As here shown the boss or hub 12 hasa central enlarged portion 12 provided with a series of bolt holes 22.The segmental portions 13 of the blades are extended eas es somewhatbeyond 120 degrees, so as to provide perforated ears 23, one of which isolfset so as to overlap the ear of the adjacent blade. The segmentalportions are also provided with holes or perforations and bolts 25 orsimilar fastening means are passed through these holes and the holes 22in the boss hub, thus fastening the blades to the boss or hub and toeach other. In this construction the segmental portions 13 of the bladesare preferably flanged outwardly, as at 26, to embrace the reduced endportions of the boss or hub, but if desired the face members'17,'shownin Fig. 4: may be applied, such members in this instance, beingperforated for the bolts 25.

The screw or propeller described is light and yet strong, the method ofconstruction is such that the blades can be. formed expeditiously inlarge quantities and with the assurance that each is an exact duplicateof the others. Consequently, if a blade is injured, the entire propellerneed not be scrapped, but the injured blade can be removedand replacedby an exactly similar one. The blades shown in Figs. 5 and 6 can bereplaced in' the field, but the propeller or screw shown in Figs. 3 anda must be returned to a shop to have the injured blade taken out and anew one put in.

The fabrication of the blades does not require such highly skilled laboror men having a special aptitude for the work asin the manufacture ofwooden propellers. After the dies have been accurately formed, itbecomes a simple die stamping operation,

and as is well known, the parts can be.

formed by die pressing to an accuracy of one one-thousandth of an inch.The electric welding can be readily and cheaply done,

and as this means merely heats the parts locally, it does not result ininjurious distortion of the blade. Care will be taken to weigh andadjust all of the component parts of a blade beforeit is assembled,determining and making their centers of gravity all alike and alsomaking their rotative Inoments alike about the center of rotation in thepropeller. If after assembling the propeller should be out of balance,it can be readily remedied, either by removing a little of the surfaceof the metal, or by adding weight at the necessary point, such as bycoating the plates with fluid metal. of any kind or adding metal in anyother form at the point where the weight is deficient.

The blades are susceptible to a very high polish on the exterior, and iffor ed of steel or other corrodible metal, can be c ated with suitablenon-corrodible. metal, preferably from the contained air. The bladeswill have their hub ends closed to prevent the entrance of moisture orother substances.

What I claim is 1. An air screw blade comprising a hollow sheet metalbody provided with longitudinally extending internal bracing and with aninternal reinforcement at the hub end extending over and enveloping thehub and projecting toward the tip of the blade.

2. An air screw blade comprising a hollow body formed or die-shapedsheet metal mem bers united at their edges and provided withlongitudinally extending internal bracing secured to the opposite sidewalls of said body and at the hub end being provided with internalreinforcement surrounding and enveloping said hub and projectingtowardthe ti of the blade.

3. in air screw blade comprising a hollow body formed of die-shapedsheet metal members welded together at their edges and provided withinternal bracings extending longitudinally of the blade and welded tothe opposite walls thereof, and at the hub end provided with internalreinforcement :extending over andj enveloping said hub andprojectingtoward. the tip of the blade.

sheets shaped to provide the proper exterior contour of the blade andunited at their edges, an internal bracing comprising continuous zig zagshaped members extending longitudinally of said body'and securedalternately to opposite side walls thereof and dividing the hollowinterior into triangular shaped cells, and internal reinforcement at thehub end extending over and enveloping the hub and projecting toward thetip of the blade.

5. An air screw or propeller blade comprising a hollow sheet metal bodyformed of sheets shaped to the proper exterior contour and united attheir edges, and internal reinforcement plates in said blade at the hubend and projecting toward the tip of the blade, both said blade andinternal reinforcement plates extending over and enveloping the hub, andsecuring means fastening both said blade and reinforclng plates to thehub.

' 6. An air screw or propeller blade comprising a hollow sheet metalbody formed of sheets shaped to the proper exterior contour and unitedat their edges, and internal-reinforcement plates in said blade at thehub end and projecting toward the tip of the blade, both said blade andinternal reinforcement plates extending over and enveloping the hub, andsecuring means extending through said blade and reinforcemeznt lates andinto tliehub.

11 air screw comprising .hollow sheet metal blades having their boss orhub ends lso formed segmental to embrace the hub and having segmentalportions of adjacent blades united, and a boss or hub embraced by saidsegmental blade portions and'united thereto by means placed in shear.

8. An air screw comprising hollow sheet metal blades having their bossor hub ends of segmental form to embrace the boss or hub and With theouter ends of the segmental portions of adjacent blades united to eachother, an internal annular bracing surrounding the boss or hub andunited to the Walls of the blades, and aboss or hub fitting in saidsegmental portions and united thereto.

9. An air screw comprising hollow sheet 15 metal portions having theirboss or hub ends of segmental form to embrace the boss or hub, a boss orhub fitting in said segniental portions, and detachable means unitingsaid blades to each .other and to 20 the boss or hub, said securingmeans being in shear.

In testimony whereof I have hereunto set my hand. 1

' EDGAR W. SUMMERS.

Witness:

GLENN H. LERESGHE.

